Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Medical Biophysics

Supervisor

Singh, Krishna K

Abstract

Endothelial cells (ECs) line the innermost layer of blood vessels and maintain vascular homeostasis. Endothelial dysfunction may lead to cardiovascular diseases (CVDs) such as atherosclerosis. Autophagy maintains cellular homeostasis by degrading and recycling unused proteins for its’ reuse. Impaired endothelial autophagy is reported in CVDs. MicroRNAs are non-coding RNAs which regulate autophagy and endothelial function. However, the exact role of miRNA in endothelial autophagy and function is unknown. To this aim, we identified miR-378-3p as the most upregulated miRNA in autophagy-deficient ECs via miRNA-array. Inhibition and activation of autophagy up- and down-regulated miR-378-3p expression, respectively. MiR-378a-3p overexpression or inhibition inversely correlated with autophagy and function in ECs. Protein Disulfide Isomerase-4 (PDIA-4) was identified as the miR-378-3p target, where loss of PDIA-4 promoted TGFβ-mediated endothelial to mesenchymal transition. The novel identified relationship between MiR-378a-3p, endothelial autophagy and function can be used to modulate/improve endothelial autophagy and function to treat CVDs in the future.

Summary for Lay Audience

Endothelial cells line the innermost layer of blood vessels, and they are responsible for maintaining normal functioning of blood vessels, specifically, dilation and constriction of blood vessels. Autophagy is the “self-eating” process that degrades damaged proteins and recycles their cellular components for their reuse. It is known that autophagy declines with age, and accumulation of damaged proteins can lead to malfunctioning cellular organelles which eventually contribute to cardiovascular disease. Dysfunctional endothelial cells arise from various factors, including dysregulated autophagy, and is the major contributor to the progression of cardiovascular diseases such as atherosclerosis. Thus, it is important to conduct research to find potential modulators of autophagy which can in turn regulate endothelial autophagy and functions. MicroRNAs are small molecules that are known to regulate gene expression by binding to their targeted genes and block their translation. MicroRNAs have been shown to effectively regulate autophagy by regulating the synthesis of essential autophagy-related proteins. This study has found miRNA-378-3p to be the potential modulator of endothelial autophagy and endothelial function. In addition, we also identified PDIA-4 as the direct target gene using computational approaches and verified using molecular biology approaches. Loss of PDIA-4 was found to promote endothelial to mesenchymal transition (End-MT), a cell differentiation process that leads to loss of endothelial function and gain of stem cell-like mesenchymal function, and End-MT is commonly associated with organ fibrosis. This is the first study that investigates the relationship between miRNA-378-3p, endothelial autophagy and endothelial function. The result from this study adds to the current knowledge of the relationship between miRNA and endothelial function and reveals a PDIA-4 as a novel target of miRNA-378-3p, which has the potential to be used to modulate/improve endothelial autophagy and endothelial function to treat CVDs and other diseases associated with impaired autophagy, endothelial dysfunction and End-MT.

Additional Files
BioRender Publication License.pdf (146 kB)
Publication permission from BioRender
Download

Share

COinS